TM 55-2210-224-122-29. MULTIPLE-UNIT OPERATION(cont)(3) Certain alarm and protective devices, and auxiliary controls such as sanding, are connected through thejumper, but the power plants and heavy duty circuits of the coupled units remain entirely independent ofeach other.b. Coupling.CAUTIONThe 80-ton locomotive can only be hooked up in multiple-unit operation withanother same model 80-ton locomotive.(1) Couple locomotives mechanically in the usual manner. Refer to paragraph 2-18.(2) Connect trainline hoses as follows:Brake Pipeto Brake PipeM. R. Equalizing Pipeto M. R. Equalizing PipeActuating Pipeto Actuating PipeIndependent Application and to Independent Application andRelease PipeRelease Pipe(3) Open cutout cocks at the ends of air lines on both units.CAUTIONTo protect multiple-unit control jumper from damage, position it up and out of theway of the drawbar.(4) Connect multiple-unit control jumper (1) to both units. Push each plug all the way into its receptacle andlock in place.c. Starting.NOTECheck that the PMCS has been performed on both units.(1) Determine which locomotive is to be the trailing unit and, ifnot already started, start in accordance with paragraphs 2-10 and 2-11.(2) Set controls on trailing unit as follows:(a) Cutoff pilot valve (2) to OUT.(b) Double-ported cutout cock (3) to CLOSED position.2-40